I was sitting in traffic and I realized how hot the bike gets. I was just wondering...how do I know if my bike is overheating? Does it feel different or does it just seize?

At idle your engine develops very little power so creates relative little heat and even on high temp days does not get that hot. It might feel hot when standing still, cause heat rises. Also, synthetic oil can stand extreme temps much better. It's usually us that get overheated and cranky when sitting in high temps with riding gear and helmet.I've idled recep aircraft engines for long periods while waiting for take-off clearance. There is little air flowing over these cowled (enclosed) engines yet the temp rarely gets above 300-325 degree which is measured at the sparkplug hole. When accelerating at 100% the temps then quikly rise to 400-450 if properly managed. So i don't sweat it too much when idling.
Cause you can always install a cylinder head temp gauge (about $75) like ithe ones used on light-sport airplanes.

bill67 wrote on 05/28/08 at 12:37:18:

If I'm gonna sit still in taffic for that long i shut're down. saves gas

I had a cyl head temp gage a long time ago.
After chugging up grapevine, it got as hot as I've ever seen it.
Tried 2 ways to cool it down, shut her down and let it coast.  And the other was to let it roll up some speed with the engine running high rpm's.  
Running cooled it faster.  Yeah it has forced air cooling, but the heads aren't completely in that breeze.
So what I want to know, was it cooling faster cause of the high rpms with the throttle at idle?
And could pulling out the choke on a hot day help?

   In my Nissan manual it says if your pulling a trailer when you stop you should let it idle in neutral for a minute before turning off motor to let it cool down some.

bill67 wrote on 05/28/08 at 14:27:51:


Bill, big difference here is you want the water pump in your Nissan to continue to pump coolant while the fan cools it.  Air cooled engines don't work like that.  If you have no air flow, you're better off shutting down with any air cooled bike assuming no forced air.

Plano Rider wrote on 09/18/08 at 16:13:09:


Hi Plano,

Check the area for an oil leak.  Oil may be dripping on to the header and causing the smoke.

IHTH!

I am afraid I must disagree. The heat is generated in the combustion chamber, not in the "internal parts of the engine." The only heat generated in the "internal parts of the engine" is that caused by friction in the moving parts, and that is a pretty low percentage of the total.

The heat is generated in the combustion chamber by burning fuel and air. The engine converts about 25% of that heat to useable work and wastes the rest. About half of the waste heat leaves the engine in the form of hot exhaust gas. The other half of the waste heat leaves via the cooling system. The heat is directly imparted to the piston, cylinder head, and cylinder walls. The heat imparted to the head and cylinder is conducted through the metal to whatever is used as a coolant, either air or water. The heat imparted to the piston is usually conducted to the cylinder walls, somtimes via the rings. Some, but not all, four-stroke engines spray oil onto the bottom of the piston crown, and that oil is used to carry away excess heat. The side effect is that the oil scraper rings have more work to do getting the excess oil off the cylinder walls. Unless specifically designed to be oil-cooled (early Suzuki GSX-R), oil carries away only about 1 to 5% of the engine heat. The oil does cool engine bearings, as well as lubricating them.

Lest anyone believe I am "picking nits," I submit for consideration the lowly two-stroke engine, widely used in such things as outboards, chain saws, and so on. Those engines do not have engine oil, except for the quite small amount that passes through them with the fuel. Therefore, they cannot depend on oil as a coolant.

I will pass on the comment about synthetic versus mineral oils, as neither is very good as a coolant. The synthetic oils are reputed to withstand high temperatures better, but that doesn't make them better as coolants.